Male Speaker: With each heart beat there are two phases in the passage of oxygenated blood and di-oxygenated blood through the heart. And the phase of relaxation diastole the heart fills with blood as the ventricles relax the valves in the aorta and in the pulmonary artery closed with the dub sound and blood pours into the two arteria from both vena cava and the pulmonary veins. The mitral and tricuspid valves between the arteria and ventricles open allowing blood into the ventricles the heart then stops filling with blood. In the phase of contraction or systolic the heart empties and lub sound is made by the closing of the mitral ans tricuspid valves. This prevents a back flow of blood into the arteria as it is pumped from the ventricles into the pulmonary artery and the aorta each heart beat last up to 8 tenths of a second with systolic lasting for 4 tenths of a second and diastolic occupying the remaining time.